This invention relates generally to guided missiles, and in particular to the guidance system of air-to-air guided missiles. In greater particularity, this invention provides a system for determining missile guidance during the handover from the passive to active tracking mode.
Upon the detection of a search radar beam from an aircraft having such an aircraft warning system therein having air-to-air guided missiles, the aircraft launches a guided missile at the target aircraft having the search radar. It is assumed that the target aircraft has not detected the bomber in the following scenario. This situation can easily occur if the bomber is flying near the deck to avoid detection from both land based radar and/or aircraft radar. The detection of the search radar from the target aircraft can occur at a distance well beyond the detection range of the search radar because of the required return energy level needed to identify the bomber. The bomber may be only one of an attacking group and certainly desires to disable the target aircraft before detection of itself or other bombers within the group. Further, it is highly desireable for the bomber to remain close to the ground as possible to avoid additional detection by land based radar. Therefore, as soon as the search radar is detected, the bomber launches an air-to-air guided missile. Because of the great range between the bomber and the target aircraft, the guided missile will remain undetected for a longer time due to the much smaller radar cross section. To minimize the distance at which the guided missile is detected, the guided missile can be flown to a much higher altitude to avoid detection by the main lobe of the search radar. The target aircraft probably is aware of such a scenario and thus would scan periodically higher altitudes.
The initial coordinates of the target aircraft are fed to the missile guidance system at launch and then the guided missile executes the low-to-high altitude maneuver and tracks passively the search radar's side lobes until transmission is halted. At this point, the guided missile must start active seeker mode tracking. Detection of the guided missile by the target aircraft may occur at distances of fifty miles or greater. This distance clearly limits the active seeker of the guided missile. Optical tracking is not feasible because of the great distance and thus radar tracking is required although still limited because of range.